Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 112012
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
212 PM MDT Fri Aug 11 2017

.SHORT TERM...(This evening through Monday)
Issued at 206 PM MDT Fri Aug 11 2017

A series of cool low pressure troughs moving across the Pacific
Northwest, the Northern Rockies and Southern Canada will converge
with warmer moist southwest flow on the west side of a flat high
pressure ridge over the Desert Southwest and Great Basin, over
Wyoming.  This will keep clouds and scattered showers with
isolated scattered thunderstorms over the area through Sunday.
Precipitation will be greatest over the mountains.  This will keep
temperatures depressed and relative humidity elevated.  With low
level north to east flow winds will be rather light outside of
thunderstorms which may produce strong erratic wind gusts.
Sunday night and Monday, west to southwest flow aloft will move
over the area with warming and drying.  Isolated showers and
thunderstorms will be possible but with much less coverage.
areas of west to southwest winds will spread from west to east
and become gusty.

.LONG TERM...(Monday night through Friday)
Issued at 206 PM MDT Fri Aug 11 2017

As a large low pressure trough moves inland along the Pacific
Northwest, southwest flow will move inland the high pressure ridge
over the Desert Southwest and Great Basin shifts east.  The Pacific
trough will also produce stronger south southwest flow over
the Northern Rockies and Southern Canada bringing an end to the
cool northwest flow.  Drying and warming will result as the flow
aloft over Wyoming shifts to the west and eventually to the
southwest.  Surface winds from the west and southwest will spread
from the west and southwest into central and eventually eastern
Wyoming through Friday.   This will significantly decrease
the afternoon and evening convection but not eliminate it
completely.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 206 PM MDT Fri Aug 11 2017

A weak disturbance will move southeastward into Montana and NE WY in
the afternoon hours today.  West-NW breezy wind expected across SW
WY, while a northerly push will come down east of the divide. The
weak front will produce shower and thunderstorm activity across
western and central Wyoming this afternoon and early evening.
Significant thunderstorms, some containing small hail, have already
formed along and moved off of the Big Horn Mountains, tracking east
across the Interstate 25 corridor in Natrona and Johnson Counties
early this afternoon. KCOD, KBYG, and KCPR should see the biggest
impact from the storms this afternoon. Most of the storminess will
diminish by 02Z/Sat, with some residual showers into tonight. The
storms are likely to produce brief heavy rain and wind gusts over 30
kts.

&&

.FIRE WEATHER...
Issued AT 206 PM MDT Fri Aug 11 2017

A series of cool low pressure troughs moving across the Pacific
Northwest, the Northern Rockies and Southern Canada will converge
with warmer moist southwest flow on the west side of a flat high
pressure ridge over the Desert Southwest and Great Basin, over
Wyoming.  This will keep clouds and scattered showers with
isolated scattered thunderstorms over the area through Sunday.
Precipitation will be greatest over the mountains.  This will keep
temperatures depressed and relative humidity elevated.  With low
level north to east flow winds will be rather light outside of
thunderstorms which may produce strong erratic wind gusts.
Sunday night and Monday, west to southwest flow aloft will move
over the area with warming and drying.  Isolated showers and
thunderstorms will be possible but with much less coverage.
areas of west to southwest winds will spread from west to east
and become gusty. Mixing heights and transport winds will combine
for generally very good to excellent smoke dispersal from  late
morning through early evening each day.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Baker
LONG TERM...Baker
AVIATION...Lipson
FIRE WEATHER...Baker



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